The manufacture of particular equipment for the telecommunications industry often requires repetitive tool movements by an operator who is sitting or standing at a work position. One commonly used piece of equipment is a terminal block which includes a plastic carrier having a plurality of metallic terminals mounted therein. Typically, portions of the terminals extend from the plastic carrier and are adapted to have conductors wrapped therabout in close-fitting relation to establish electrical connections. In other applications, nuts must be turned into terminal nests or screws turned into sockets. The wrapping of conductors about these terminals or the turning of screws or nuts is generally accomplished in a factory environment by an operator who uses a tool throughout a work shift. The typical tool for these kinds of applications is pneumatically operated and includes a barrel and a working portion such as a bit, for example, which includes an opening for receiving a terminal to be wrapped.
In some instances, it is best to position the workpiece so that the tool is moved horizontally inwardly and then withdrawn in each cycle of operation. For those, the tool is generally hand-held through a pistol-type grip which is attached to the barrel. For example, see U.S. Pat. No. 4,330,093 which issued on May 18, 1982 in the name of I. B. Chapman.
In an alternate method, the workpiece is supported in a manner which requires that the tool be moved vertically. For this workpiece orientation, a tool which is characterized as being in-line or straight is used. In such a tool, a motor, and a barrel are in-line. There is no pistol-type grip; instead, the barrel is gripped by the operator. The tool is moved vertically from a rest position in which it is suspended above the workpiece to a work-engaging position where the bit engages the workpiece.
The movement of the in-line tool in a vertical manner may cause biomechanical problems for the operator because of the relative vertical locations of the rest position of the suspended in-line tool and of the workpiece. The grasping of the barrel in the rest position by the operator may result in what is referred to as an ulnar deviation of the forearm. The ulnar bone deviates from its normal anatomical position with respect to bones in the carpal tunnel area of the hand. This causes compresssion of bones in the carpal tunnel area and extension of muscles of the forearm. Over a period of time, repetitive extension together with a relatively tight grip, which is necessary to move the tool downwardly against the upward bias of a tool support system, may result in operator fatigue and in product defects.
This last mentioned problem has been addressed by a prior art arrangement in which the barrel is fitted with a molded sleeve having a flange at one end thereof. The sleeve is made of plastic and is caused to contract about the barrel to become secured thereto. The flange is engaged by the ulnar side of a user's hand which grips the sleeved barrel. This facilitates the application of forces to the tool to move it downwardly from the rest position to the work-engaging position without requiring the relatively tight grip as before. Inasmuch as the sleeve must be cut in order to be removed, it is important that it not extend beyond the barrel; otherwise, it would be difficult to replace or to repair the working portion of the tool. Consequently, while this arrangement avoids the necessity for gripping the tool tightly in order to move it to the work-engaging position, the distance of the gripped portion of the tool from the workpiece remains unchanged and may still result in an undesirable degree of ulnar deviation. Another disadvantage of this arrangement is the requirement of sufficient inventory of sleeves of different sizes to fit barrels which vary in cross-section.
Another problem with in-line type tools relates to the distance of the hand-gripped portion of the tool from the end of the working portion. For example, it is not uncommon for the end of a wire-wrapping bit to be spaced as much as four inches from the barrel. A high degree of manual dexterity is required to maintain the working portion of the tool in alignment with the workpiece as the tool is moved downwardly. This problem also occurs with respect to the priorly-described plastic sleeve which it will be recalled is attached to the barrel with the flange displaced the same distance from the working portion as is the barrel.
What is required and what seemingly is not available in the prior art is an in-line tool which is adapted to be moved vertically in a repetitive manner between a rest position and a work position without causing operator fatigue and one which facilitates tool and workpiece alignment. The sought-after in-line tool should include provisions which are capable of easily being tailored and secured to any number of commercially available in-line tools.